Encodingversion v1.0.0

QR Code Generator

An ISO/IEC 18004 encoder written from the specification: versions 1 to 40, error correction L/M/Q/H, numeric, alphanumeric and byte modes. Type a payload and the symbol appears here; pipe one to curl and a scannable code is drawn in your terminal, quiet zone and polarity both correct.

Payload

Error correction

M (~15% recoverable) is the general-purpose level and the default. L (~7%) fits more data in a smaller symbol but leaves less margin for a code read at an angle. Q (~25%) and H (~30%) are for codes that will be printed, laminated or overprinted with a logo.

Version

Auto picks the smallest symbol that fits. Pinning a version keeps a series of codes the same physical size.

Terminal

Half blocks, no colour. On a dark background pass ?invert=on.

Not encryption

A QR code is an encoding, not encryption. Anyone who can photograph this can read it.

A wifi password, a TOTP seed or a payment link inside a code is readable by every phone that sees it, including one pointed at your screen from across the room.

Privacy

Everything on this page is encoded in your browser. Nothing is uploaded.

Your payload never reaches the server, a query string, a log or local storage — the page imports the same module the API uses and runs it here. Refreshing discards everything.

Black on white, always

The symbol keeps its own white card in a dark theme, and the SVG is not theme-aware. A QR code is dark-on-light or it is out of spec: inverting it to match the page would look better and scan worse. The four-module quiet zone around it is part of the code, not padding.

Encoder notes

Uppercase packs denser: HTTPS://EXAMPLE.COM is alphanumeric mode, https://example.com is byte mode and often a version larger.
One mode is chosen for the whole payload. Splitting a mixed payload into numeric and alphanumeric runs would sometimes save a version; it is not done here.
Kanji mode is not used. The input is bytes, so there is nothing to transcode from — byte mode encodes any Kanji payload correctly, just less densely.
Byte mode emits no ECI header, which is what every deployed decoder expects.
Reading a QR image is out of scope. Your phone camera already does it well.

From the command line

The same URL answers a POST with a scannable code drawn in half-block characters, quiet zone included, ready for a phone held up to the screen. Use printf, never echo: the body is encoded exactly as received, so echo’s trailing newline ends up inside your URL.

$printf 'https://tools.primeforge.app' | curl -fsS --data-binary @- https://tools.primeforge.app/qr

$printf 'hi' | curl -fsS --data-binary @- 'https://tools.primeforge.app/qr?format=text&invert=on'

$printf 'WIFI:T:WPA;S:office;P:hunter2;;' | curl -fsS --data-binary @- 'https://tools.primeforge.app/qr?ec=q&format=svg' > qr.svg